Follow-up: Remove NULL_DISPUTE_KIT references

[coderabbitai]

Follow-up to: #1813 (comment)
PR URL: #1813
Requested by: @jaybuidl

It appears that NULL_DISPUTE_KIT is still used for critical business logic in KlerosCoreBase. The constant is deprecated but removing it is non-trivial. This issue tracks the eventual removal or refactoring of NULL_DISPUTE_KIT references as part of a larger refactoring.

[jaybuidl]

Putting this PR on hold because it would break the current production deployment after upgrade. It would require some dispute migration logic in the initializer and a fair amount of testing/simulation.

In addition the subgraph refers to the dispute kit classic index at 1 in a number of places.

• localDisputeID = `1-${disputeID}`;
• disputeKitID = "1";
• Comment about ID 1
• export const DISPUTEKIT_ID = "1";
• classicDispute = new ClassicDispute(`1-${coreDisputeID}`)

Overall it's a high risk/low value change.